An electromagnetically-driven fuel injector in general drives a needle to be opened by electromagnetic force generated when a drive coil is energized. At this time, since a valve-opening characteristic of the fuel injector is varied depending on a drive current profile (drive current waveform) of the fuel injector, a valve-opening speed of the fuel injector is greatly affected by a variation in a drive current profile, particularly a variation in a peak current value (a peak value of the drive current), and thus an injection amount tends to further vary with a smaller injection amount of the fuel injector.
In an exemplary case as described in Patent Literature 1, a current detection section that detects a drive current of a fuel injector is provided, and a drive current of the fuel injector is controlled to have a target drive current profile based on the drive current (detected current) detected by the current detection section. In Patent Literature 1, a variation in the drive current due to a machine-difference variation in the current detection section or the like is beforehand measured for each control device, and a control target value (a target value of a drive current or drive time) of the fuel injector is corrected based on the variation in the drive current (current difference value).
For example, the detected current of the current detection section may shift due to aging variation or the like. If the detected current shifts, control accuracy of the drive current of the fuel injector is reduced. Hence, if the detected current of the current detection section shifts, such a shift in the detected current is preferably early detected. However, the technique of Patent Literature 1 cannot determine the shift in the detected current of the current detection section (cannot determine whether or not the detected current is correct). Hence, the technique cannot early detect shift in the detected current if the detected current shifts.